Reverse feed two thread chainstitch sewing machines



v. J. SIGODA 3,150,622

REVERSE FEED 'rwo THREAD CHAINSTITCH sswmc MACHINES Sept. 29, 1964 6 Sheets-Sheet 1 Filed May 3, 1963 INVENTOR. V/crol {1..5/6004 p 29, 1954 v. J. SIGODA 3,150,622

REVERSE FEED TWO THREAD CHAINSTITCH SEWING MACHINES Filed May 3, 1963 6 Sheets-:Sheet 2 INVENTOR. l l Q J. S'eoo A T'TOQNEY Sept. 29, 1964 v. J. SIGODA 3,150,622

REVERSE FEED TWO THREAD CHAINSTITCH SEWING MACHINES Filed May 3, 1963 6 Shee ts-Sheet I5 IN TOR. v V/Crof J- lG-OD4 Sept. 29, 1964 v. J. SIGODA 3,150,622 I REVERSE FEED TWO THREAD CHAINSTITCH SEWING MACHINES Filed May 3, 1963 6 Sheets-Sheet 4 INVENTOR. were J. 5/6004 ATTOPNEY Sept. 29, 1964 v. J. SIGODA REVERSE FEED TWO THREAD CHAINSTITCH sswms MACHINES 6 Sheets-Sheet 5 Filed May 3, 1963 V. J. SIGODA Sept. 29, 1964 REVERSE TWO THREAD CHAINSTITCH SEWING MACHINES 6 Sheets-Sheet 6 Filed May 3, 1963 United States Patent York Filed May 3, 1963, Ser. No. 278,529 16 Claims. (Cl. 112--197) This invention relates to two thread chainstitch sewing machines and more specifically to a new version of such machines which can produce such chainstitching when the usual feed movement of the work through the machine is reversed or otherwise changed.

Basically two thread chainstitching is produced by the successive interceptions of the needle thread loop by a threaded underlooper, and of the underlooper thread loop by the needle as it enters the so called underlooper thread triangle. The proper formation of this thread triangle is essential to stitch formation and this in turn depends largely upon the action of the feed mechanism of the sewing machine which normally draws the work rearwardly from the stitch forming region. One anchorage for the triangle is the eye of the underlooper. Another is the needle thread looped about the underlooper thread in the preceding stitch sewn in the work. When the feed action is effective in the usual direction, the movement of the work rearwardly drawing this last anchorage with it, causes elongation of the thread triangle. It is into this elongated thread triangle that the needle subsequently descends.

However, as the feed movement is reduced this elongation is lessened, and when the feed movement is reversed, the thread anchorage in the work is drawn forwardly, eliminating the thread triangle so that the needle cannot intercept the underlooper thread and thus the stitch is skipped.

In producing certain types of work, it is desirable to reverse the feed movement of the fabric through the machine. In tacking operations, a series of stitches is sewn in one direction, and another series of stitches is then sewn in the opposite direction over the first series, and so on until the desired secureness has been provided.

Compared to lockstitching, one of the drawbacks of two thread chainstitching is that it can be unravelled from the end of the stitching. However, it is virtually impossible to unravel the threads from the beginning of the two thread chain-stitching. In garment constructions utilizing two thread chainstitching, this shortcoming requires that the start of the stitching be made at the point of a seam at which the greatest stress during wear is experienced to minimize the possibility of failure of the seam by unravelling under tension. This limitation that the seam be started at the point of heaviest loading imposes a restriction on the garment design engineer which prescribes the sequence of manufacture regardless of convenience and thus hampers the natural flow of production. This is overcome in some cases by an additional sewing operation on another type of machine such as a lockstitch or bar tacker to apply more stitching at the critical points under stress. Such additional operations are undesirable because of disruption of the flow of production.

lowever, if the direction of feed could be reversed at will, as can be done with certain typesof lockstitch sewing machines, such additional sewing operations would no longer be required. The seam could be sewn to the point of stress, the feed movement reversed, and a series of stitches sewn in the opposite direction. This would lock the point of stress by what in effect is the start of ice a new line of two thread chainstitching at the point of reversal. Thus in one sewing operation, both the desired sturdiness of seam construction and convenience of manufacture could be achieved.

Previously this has not been possible since the available two thread chainstitch sewing machines have not been provided with reverse feed mechanisms because of the inability to avoid skipping stitches when the feed movement is reversed. It is possible, however, to produce a two thread chainstitching machine by attaching additional mechanism to converted lockstitch sewing machines, some versions of which are provided with reverse feed mechanisms. One way in which this can be done is disclosed in application Serial No. 30,682, filed May 20, 1960, now Patent No. 3,121,413. Without the mechanism subsequently described herein, such converted lockstitch sewing machines are also inherently incapable of producing satisfactory two thread chainstitching when the feed movement is reversed.

Briefly, as disclosed in the mentioned patent application the mechanism which is added to the converted lockstitch machine to produce two thread chainstitching includes an underlooper moving transversely to the feed direction, and a two-limbed underlooper thread presenter moving along the line of feed which engages the underlooper thread to form the thread triangle base line, the latter being disposed transversely to the line of feed. With this arrangement, the position of the underlooper with respect to the descending needle is no longer critical and a much shorter, sturdier, and therefore steadier, needle may be used at higher speeds. It is also possible to operate the underlooper with a simple bidirectional movement rather than the compound or four motion movement usually required for needle thread seizure and needle avoidance.

When this mechanism is incorporated into a lockstitch sewing machine, such as the Singer 451K class (one variety of which, the type 451K 145, has a reverse feed mechanism which the operator may utilize by merely depressing a lever), the usual rearward feed movement of the work through the machine cannot be disturbed without affecting the proper formation of the two thread chainstitching. Any movement of the work through the machine other than in the rearward direction will pull the underlooper thread from its engagement about the limbs of the presentor and this will alter the underlooper thread triangle to such an extent so that it cannot be intercepted by the descending needle.

In any type of sewing machine, the feed movement of the work can be ettected either by reducing the spring pressure exerted on the presser foot or by raising the presser foot slightly so that the normal feed action on the work is ineffective to move the work in the usual direction. The operator can then feed the work manually in any desired direction. This manipulation by the operator makes it possible to tack the start or end of the seam. However, since any change of direction of feed, particularly reversal thereof, destroys the thread triangle in two thread chainstitching sewing machines, this invention aims at removing this disadvantage by preserving the underlooper thread triangle for interception by the needle regardless of the direction of feed of the work or any change or reversal of such direction.

This aim is accomplished according to the invention by a new underlooper thread interceptor which operates in conjunction with the mentioned thread presentor and which is added, with its operating means, to the mechanismwhich is attached to the lockstitch sewing machine when it is converted for two thread chainstitching according to the mentioned patent application. It is an advan- 35 tage of the invention that this new arrangement is effective regardless of the stitch length or feed rate as well as change in direction of feed.

Some earlier attempts have been made to prevent skipped stitches on feed direction change or reversal in two thread chainstitch machines such as that shown in Onderdonk Patent No. 1,087,817 of February 17, 1914, and Motfatt Patent No. 1,618,213 of February 22, 1927. However these efforts were confined to the compound or four motion type of underlooper operation whereas the present arrangement is suitable for use with such machines using an intermediate element such as the presentor of the mentioned patent application about whose limbs the underlooper thread triangle is originally based and about which the destroyed thread triangle may be reformed by the action of the interceptor when the feed movement is changed or reversed.

This application is a continuation-in-part of application Serial No. 151,680 filed November 13, 1961, and now abandoned.

Preferred embodiments of the invention are disclosed in the following description and illustrated in the drawings in which:

FIG. 1 is a view in plan showing the general organization of the device with various portions in section to illustrate details of structure of the operating means for the underlooper thread interceptor;

FIG. 2 is a front elevation corresponding to FIG. 1, indicating how the mechanism is attached to the sewing machine, with portions broken away to show constructional details;

FIG. 2a is an enlarged detail view showing the thread triangle a, b, c, formed by the enchaining of needle thread xx and underlooper thread y-y, wrapped about the limbs of the presentor, when the work is being drawn in the normal rearward direction by the feed mechanism of the sewing machine, the work fabric having been omitted for clarity;

FIG. 3 is an enlarged detail view showing how the interceptor acts to retain the underlooper thread to prevent destruction of the thread triangle when the feed action is reversed and the work is fed forwardly;

FIG. 4 is an end view taken on line 4-4 of FIG. 2;

FIGS. 5 and 6 are detail views in perspective showing the position of the interceptor in relation to the needle, underlooper and presentor at both extremes of movement;

FIG. 7 is a view in plan generally similar to FIG. 1, showing another form of operating mechanism for the underlooper thread interceptor;

FIG. 8 is a composite view of the mechanism of FIG. 7, the left portion being an end view generally similar to FIG. 4, and the right portion being a front elevation generally similar to FIG. 2;

FIG. 9 is a bottom plan view of a sewing machine having a reverse feed mechanism such as is disclosed in Meloy Patent No. 2,681,627, showing a third form of operating mechanism for the underlooper thread interceptor;

FIG. 10 is side elevation of the mechanism shown in FIG. 9;

FIG. 11 is a top plan view showing the operating mechanism for the underlooper thread interceptor of FIG. 9;

FIG. 12 is a fragmentary sectional view taken subtantially on line 1212 of FIG. 9; and

FIG. 13 is a schematic diagram of the feed advance mechanism of the machine illustrated in FIG. 9, the position of the parts for normal feed advance being illustrated in full line and for reverse feed being illustrated in broken line.

This invention operates in the environment of the two thread chainstitching mechanism disclosed in patent application Serial No. 30,682, now Patent No. 3,121,413

ithe relevant parts of which will be but briefly described herein, it being understood that further details are available from that patent.

The sewing machine has a cloth-plate 1 on the underside of which there is a downwardly projecting box 60 normally sealed off by a gasketed cover plate which is replaced by a support casting 64 when the converting mechanism is installed. Drive shaft 9 driven from the main-shaft, projects into this box and in the conversion is fitted with gears 24 and 62 (FIG. 2).

Gear 24 is in mesh with gear 11 mounted on shaft 12 which normally carries in eccentric-block at its other end. This block carries an eccentric-pin 29 which fits within the bore of an antifriction bearing 35 retained in the enlarged portion of a strap-link 32 pivotally connected by pin 34 fitting freely in a bushed opening in presentor carrying arm 30 which is oscillatably mounted on shaft 31. Presentor 36 carried by arm 30 is thereby oscillated about shaft 31 to travel along the line of feed.

Gear 62 through a train of gears 71, 72 and 76 rotates an eccentric-block carrying eccentric-stud 80 which through pitman 81 and rocker arm 86 rocks looper carrier 88. Underlooper 89 supported by carrier 88 is thus oscillated transversely to the feed line.

One form of the additional mechanism which is added to drive the underlooper thread interceptor, shown in FIGS. 1 to 6, is arranged so that the interceptor travels along the line of feed but in opposition to the direction of travel of the presentor. In this version, the interceptor moves on a raised path to intercept the underlooper thread and is then actuated by a cam track to carry the thread rearwardly and toward the opposite side of the needle path. This new mechanism includes eccentric 101 which is fastened on shaft 12 and which carries eccentricpin 29 to operate the presentor carrying arm 30. Eccentric 101 is encircled by an anti-friction bearing 102 retained within the bore of a strap-link 103 whose free end terminates in a boss 104 which has an extension in the form of a slotted pinch-clamp 105. Boss 104 is provided with a transverse bore whose size can be reduced by tightening the screw in pinch-clamp 105 and in which bore eccentric-stud 106 is retained.

Support bracket 108 consisting of two arms 109 and 110, secured together at 111, is pivotally mounted on stand shaft 31 which already carries the support arm 30 for presentor 36. In this new arrangement, the width of hub 41 of arm 30 is reduced so that the bushing inserted within its bore and which fits over shaft 31, has two projecting shoulders 112 and 113. The lower ends of arms 109 and 110 are provided with openings which fit freely over these projecting shoulders 112 and 113, and hence bracket 108 can oscillate about shaft 31 independently of the opposed oscillatory movement of presentor support arm 30.

Bracket 108 is oscillated from eccentric 101 through a pivotal connection provided at the bushed opening 114 in extension 115 of arm 109 by the projection 116 of stud 106. Since this portion is eccentric with respect to the shank 117 of the stud, a small amount of positioning of bracket 108 about shaft 31 can be obtained by rotating stud 106 in the bore of boss 104. This position may be adjusted by inserting a screw driver blade into the slot in the head of stud 106 to turn the stud after pinch-clamp 105 has been loosened. This permits some fine regulation of the position along the line of feed of the interceptor with respect to the underlooper thread and this determines how far rearwardly the thread can be carried.

The upward end of arm 109 of bracket 108 continues into a horizontally disposed support platform 118 near the free end of which vertical support boss 119 is provided for a pivotally mounted carrier 120 to which the underlooper thread interceptor 121 is secured. It may be desirable to provide for some adjustment of the position of this pivotal mounting transversely with respect to the line of feed, and this may be readily accomplished by utilizing some variation of the mounting arrangement of stud 106 with its eccentric shoulder. This of course is a mechanical detail well within the skill of those versed in the art.

The free end of interceptor 121 is notched at 123 to retain the underlooper thread after interception. As may be noted in FIG. 1, since the underlooper thread is caught about the underside of the limbs of the presenter 36 and rises along the outer side of the right limb, notch 123 is lined up so that as the interceptor moves rearwardly, the notched end moves along the outer side of this limb to intercept the underlooper thread within the notch.

Carrier 120 is provided with cam track 124 into which pin 125 depending from the undersurface of the bed 1 of the sewing machine, fits to guide interceptor 121 as it moves bodily along the line of feed on its pivotal mounting about shaft 31. It is apparent that it is a matter of choice whether the pin 125 be aflixed to the machine bed or to the carrier 120. In the latter case, the cam track would be incorporated in a member which would be affixed to the underside of the sewing machine bed.

The contour of the cam track has been selected so that the notched end of the interceptor follows a prescribed path at first rearwardly alongside the outer side of the right limb of the presentor to intercept the underlooper thread, and then both rearwardly and transversely toward the opposite side of the presentor. As viewed in FIG. 1, this would be toward the left side of the needle path and to the rear thereof. The transverse movement of the underlooper thread need only be to a point just beyond the center line of the needle path, although obviously it could be continued to any desired distance beyond the needle path. What is of importance is that the thread triangle is established with one anchorage about the side of the right limb of presentor 36 and another anchorage about the notched end of the interceptor rearwardly and toward the side of the needle path opposite to that of the anchorage about the right limb of the presentor. It is the positioning of the thread triangle in this manner which is the distinguishing feature of the invention and which provides the sure interception of the underlooper thread by the descending needle when the usual rearward feed direction of the work is changed either by manipulation of the presser foot by the operator or by automatic operation of the feed reversal mechanism of the sewing machine shown in the Meloy Patent No. 2,681,627.

The underlooper thread engaging stroke of the interceptor 121 is timed so that the interceptor begins to move rearwardly just after the work transporting horizontal component of the feed action begins, regardless of the direction of feed. When the-work is being fed rearwardly in the normal direction of travel through the machine, the underlooper thread caught on the underside of the limbs of presentor 36 and held at the top by the anchorage, as shown in FIG. 2a, at c (which is actually within the work being sewn), formed by the enchainment of the x-x needle and the yy underlooper threads in the preceding stitch, has a vertical inclination to the rear, the extent of which depends upon the stitch length or feed stroke. When the stitch length is at its greatest, the inclination will be shallow. When the stitch length is at its shortest, the inclination will be steep and almost approach the vertical. When the direction of feed is reversed, with the work being fed forwardly, the respective inclinations will be toward the front rather than toward the rear of the machine.

The notched end of the interceptor will always engage the inclined underlooper thread, regardless of the direction of inclination, but when the feed movement is in the normal direction indicated in FIG. 2a, the interceptor will have less effect on the underlooper thread to carry it rearwardly since the thread will already be rearwardly 6 inclined. Any engagement which the interceptor effects with the underlooper thread when the feed movement is in the usual direction will thus act only to make interception by the needle of the underlooper thread more effective. When the feed movement is altered or reversed, the forward movment of the work carries the anchored underlooper thread into the path of the rearwardly moving interceptor so that positive engagement of the inclined underlooper thread begins immediately.

In FIGS. 7 and 8 there is shown a second version of the interceptor operating mechanism which functions generally in the same manner as the first version except that the interceptor has a simpler arcuate movement across the line of feed rather than the more complex movement provided by the cam mechanism of the first version. Furthermore the operating power is taken from a different portion of the two thread chainstitching mechanism which is added in the conversion of the lockstitch sewing machine. This latter feature has the advantage that it makes the timing of the movement of the interceptor independent of the timing of the movement of the presentor.

In this modification shaft has secured to its forward end eccentric-block 131 from which pin 132 extends. Pin 132 is secured to the inner race of an antifriction bearing the outer race of which is retained within the bore of a hexagonal pivot block 133. Block 133 has a pair of opposed lugs 134 freely retained in yoke arms 135 of connecting rod 136. The other end of rod 136 carries a ball joint 137 which connects with the interceptor support member 138 at 139. Member 138 is pivotally mounted on pin 140 which is supported by block 141 which in turn is attached by its pinch-clamp to shaft 31. e

The upper end of member 138 has a pinch-clamp 142 which retains the shank of interceptor 143.

. Upon rotation of shaft 130 the notched end of interceptor 143 will oscillate horizontally about the vertical axis of pin 140. Since the parts are proportioned so that the notched end of the interceptor is in position to intercept the underlooper thread leading from the limbs of the presentor, this form of interceptor functions in the same manner as the first version but on an arcuate path rather than on a compound path. But since the adjusted position of eccentric-block 131 on shaft 130 may be shifted, the timing of the movement of the interceptor is adjustable independently of the movement of the presentor.

In FIGS. 9 to 11 there is shown a third version of operating mechanism for the interceptor which differs from the second version only in that it also provides a compound movement of the interceptor somewhat similar to that of the first version. Referring to FIG. 11, support yoke 144 is provided with a pair of bushed openings by which it is mounted for oscillation about horizontally disposed shaft 31 and an extension 145 (see FIG. 10) having a vertical bore in which a headed pivot pin 146 is retained by set screw 147.

Pin 146, which is the counterpart of pin 1400f the second version, furnishes a vertical axis about which the modified form of interceptor holder 148 is rocked by the means previously described for holder 138. This includes eccentric 131, pin 132, block 133, connecting rod 136 and ball joint 137 which connects with holder 148 at 149.

Rocking of interceptor holder 148 about shaft 31 is derived from the feed lift shaft 150 of the sewing machine (see FIG. 11) rather than from the operating means for the two thread chainstitch mechanism as in the first version.

Arm 151 affixed by a pinch clamp to shaft 150, has an extension 152 to which is pivotally connected link 154 which has an offset end 155 pivotally connected to head 156 of pin 146. As the feed lift shaft rocks, interceptor 143 rocks about horizontally disposed shaft 31 and concurrently, also rocks about vertically disposed pin 146 to provide compound movement of the interceptor.

The feed operating and reversing mechanisms which form no part of the invention herein, are shown and fully described in the mentioned Meloy Patent No. 2,681,627. Only the significant features thereof will briefly described herein.

Bed 1 is suitably journalled to support bed-shaft 160 which carries the grooved pulley 161 to which power is transmitted by cogged belt 162 to operate the feed mechanism and the two thread chainstitch underlooper operating mechanism which is applied in the conversion of the basic lockstitch machine.

The feed operating mechanism includes the feed bar 164 and feed dog 165 shown in FIG. and indicated in the schematic representation of FIG. 13. Feed lift movements are derived from feed lift shaft 150 which is oscillated by crank 166, the latter being connected through pitman 168 with eccentric 169 fastened to bed shaft 160. Shaft 150 carries crank 170 which operates to raise and lower feed-bar 164.

The feed-advance movements of feed-bar 164 are derived from feed-advance shaft 171 through the conventional connection consisting of pintles 172 secured to the usual feed-rocker 173 integral with shaft 171.

Reversible oscillation of feed-advance shaft 171 is derived from eccentric 174 carried by shaft 160. The eccentric reciprocates pitman 175 connected at its opposite end to wrist-pin 178 which forms the joint of a toggle. Wrist-pin 178 is connected to two diverging toggle links 179 and 180, link 179 being connected at its opposite end to anchor shaft 181, and link 180 being connected at its opposite end by crank-pin 182 to crank 183 secured to the feed-advance shaft 171. Thus as the bed-shaft 160 is rotated, eccentric 174 through pitman 175 imparts movement to links 179 and 180 which cause crank 183 to rock the feed-advance shaft 171.

Anchor-shaft 181 is supported by arm 184 integral with stud 185 which is journalled in a boss on the underside of the machine bed. The other end of the anchorshaft is carried by an arm 186 fixed to the feed-reversing shaft 188 suitably journalled in bosses depending from the bed of the machine.

The feed reversing shaft is normally biased by spring means so that the parts are in the arrangement indicated in solid line in FIG. 13 which represents the position for normal feed-advance. Either manual means as shown in the Meloy patent or pedal means may be provided to temporarily turn shaft 188 so that the parts are arranged as indicated in broken line in FIG. 13 which represents the feed-reverse position.

It will be appreciated that as eccentric 174 is rotated pitman 176 will move toggle links 179 and 180 about their respective pivots 181 and 182. In the solid line arrangement or normal feed advance position, this will tend to straighten the toggle and thus move feed dog 165 in the direction of the arrow A. When the location of pivot 181 is shifted to the broken line position by rotation of shaft 188, reciprocation of pitman 175 by eccentric 174 will tend to break the toggle and rock the feed-advance shaft 171 so that the feed dog will move in the opposite direction shown by arrow B.

A more comprehensive description of the feed-advance and reversing mechanism and its operation may be obtained from the patent mentioned.

Although several embodiments of the operating mechanism for the interceptor have been shown and described, it is to be understood that various modifications may be made in the several parts and in their arrangement without departing from the general principles and the scope of the invention is therefore defined by the appended claims.

What is claimed is:

1. A two thread chainstitch sewing machine having stitching mechanism including a threaded needle moving on a reciprocating path, a threaded underlooper cooperating therewith, and a thread presentor which engages the underlooper thread to form a thread triangle for subsequent entry by the needle as it reciprocates on its path,

with one anchorage of the thread triangle disposed about said presentor; and means for engaging the underlooper thread between said anchorage about the presentor and the previous stitch to ensure the formation of the underlooper thread triangle about said presentor regardless of the direction of the work through the machine, said means comprising a thread interceptor mounted for movement across the line of feed and mechanism for moving the interceptor to engage the underlooper thread so that said thread extends across the line of feed transversely from the front to the rear of the needle path.

2. A two thread chainstitch sewing machine having feed mechanism including means whereby the direction of feed may be selectively reversed; stitching mechanism including a threaded needle moving on a reciprocating path, a threaded underlooper cooperating therewith, and a member cooperating with the needle and underlooper in the stitch formation, said member engaging the underlooper thread to form a thread triangle, with one thread anchorage disposed about said member, for interception by the needle as it reciprocates on its path; and means for engaging the underlooper thread between its anchorage about said member and the previous stitch to reform the thread triangle about said member when the direction of feed is reversed.

3. A sewing machine in accordance with claim 2 in which the thread triangle formed about said member has a base line disposed transversely to the line of stitching, and in which the means which engages the underlooper thread to reform the thread triangle when the direction of feed is reversed comprises a thread interceptor mounted for movement on a path generally along the line of feed, means for moving said interceptor along said path, and operating mechanism associated with the interceptor to shift it transversely of said path as it moves along said path; said interceptor, means and mechanism acting to change the original base line into one side of the thread triangle disposed about said member, and to form a new base line of underlooper thread engaged about said means; said new base line running from one side of the needle path toward the other side thereof and to the rear thereof.

4. A two thread chainstitch sewing machine having feed mechanism including means whereby the direction of feed may be selectively reversed; stitching mechanism including a threaded needle moving on a reciprocating path and a threaded underlooper cooperating with the needle; a member mounted for oscillation along the line of feed to engage the underlooper thread, said member having two spaced, horizontally disposed limbs between which the needle moves, and about which the thread of the underlooper is engaged to form a triangle for entry therein by the needle; and means for intercepting the underlooper thread and for carrying said thread from its engagement about one of said limbs toward the other of said limbs when the feed action is reversed.

5. A sewing machine in accordance with claim 4 in which said member has a right limb and a left limb, and in which the intercepting means is an interceptor having an end adapted to engage the underlooper thread, said interceptor being mounted for movement rearwardly on a path generally along the line of feed, means for moving said interceptor along said path, and operating mechanism associated with the interceptor to shift it transversely of said path as it moves along said path, whereby the interceptor is caused to travel along the side of the right limb to intercept the underlooper thread and toward the opposite side of the needle across both limbs to the rear of the needle path when the direction of feed is reversed.

6. A sewing machine in accordance with claim 5 in which additional means are provided for rocking the interceptor about a horizontal axis for the rearward movement along the line of feed.

7. A sewing machine in accordance with claim 4 in which the underlooper thread intercepting means includes a pivotally mounted carrier which oscillates about a horizontal axis along the line of feed and a thread engaging member carried thereby which is pivotally mounted on said carrier, and in which additional means are provided for guiding the thread engaging member on a prescribed path as the carrier is oscillated about its horizontal axis.

8. A sewing machine in accordance with claim 7 in which the thread engaging member guide means includes cam means contoured to direct the thread engaging member to move transversely from one side of the needle path toward the other side of the needle path as the carrier moves rearwardly about its axis.

9. A sewing machine in accordance with claim 8 in which the cam means includes a pin depending from the undersurface of the clothplate of the sewing machine and a cam track in the carrier which is engaged by the pin.

10. In a two thread chainstitch sewing machine having feed mechanism including means whereby the direction of feed may be selectively reversed; stitching mechanism including a threaded needle moving on a reciprocating path, a threaded underlooper cooperating with the needle; an underlooper thread presentor cooperating with the underlooper and the needle in the stitch formation; an eccentric for operating the presentor, means cooperating with the eccentric for rocking the presentor about a horizontal axis along the line of feed; and means for engaging the underlooper thread to ensure interception thereof by the needle when the feed direction is reversed, including an underlooper thread interceptor mounted for movement rearwardly along the line of feed; and means for mounting the interceptor for rocking about the same horizontal axis from the same eccentric in opposition to the movement of the presentor.

11. A sewing machine in accordance with claim 10 having a horizontally disposed shaft for supporting the presentor, a presentor support member pivotally mounted thereon for oscillation thereabout along the line of feed; an interceptor support member also pivotally mounted on said shaft for oscillation thereabout along the line of feed; and means connected with said eccentric for deriving the respective oscillations of each of said support members independently.

12. A sewing machine in accordance with claim 11 having a horizontally disposed shaft for supporting the presentor, a presentor support member pivotally mounted thereon for oscillation thereabout along the line of feed;

a bracket also pivotally mounted on said shaft for oscillation thereabout along the line of feed, a carrier pivotally mounted on said bracket for movement about a vertical axis, said underlooper thread interceptor being supported by the carrier; together with cam means adapted to move the carrier about its vertical axis as it oscillates about the shaft.

13. A sewing machine in accordance with claim 1 in which the mechanism for moving the interceptor comprises a support having a substantially vertical axis, and a carrier for the interceptor pivotally mounted on said support for rocking about said axis.

14. A sewing machine in accordance with claim 13 having a rotatable eccentric connection with the operating mechanism for the sewing machine for rocking the interceptor carrier about said axis.

15. A sewing machine in accordance with claim 1 in which the mechanism for moving the interceptor comprises a support shaft having a horizontal axis for pivotally supporting the presentor for oscillation thereabout along the line of feed, a bracket member also pivotally supported on said shaft for oscillation about said horizontal axis, mechanism for oscillating said bracket member about said axis, means on said bracket member for supporting an interceptor holder for oscillation about a substantially vertical axis, an interceptor holder pivotally mounted on said bracket, and mechanism for oscillating said interceptor holder about said vertical axis as the bracket member oscillates about said horizontal axis.

16. A sewing machine in accordance with claim 15 in which the mechanism for oscillating the bracket member about its horizontal axis includes a crank connection with the feed operating mechanism of the sewing machine and in which the mechanism for oscillating the interceptor holder about its vertical axis includes a rotatable eccentric connection with the operating mechanism of the sewing machine.

References Cited in the file of this patent UNITED STATES PATENTS 1,290,048 Barron et a1. Jan. 7, 1919 1,618,213 Moifatt Feb. 22, 1927 1,825,513 Erisson Sept. 29, 1931 2,046,928 Riviere et al. July 7, 1936 

2. A TWO THREAD CHAINSTITCH SEWING MACHINE HAVING FEED MECHANISM INCLUDING MEANS WHEREBY THE DIRECTION OF FEED MAY BE SELECTIVELY REVERSED; STITCHING MECHANISM INCLUDING A THREADED NEEDLE MOVING ON A RECIPROCATING PATH, A THREADED UNDERLOOPER COOPERATING THEREWITH, AND A MEMBER COOPERATING WITH THE NEEDLE AND UNDERLOOPER IN THE STITCH FORMATION, SAID MEMBER ENGAGING THE UNDERLOOPER THREAD TO FORM A THREAD TRIANGLE, WITH ONE THREAD ANCHORAGE DISPOSED ABOUT SAID MEMBER, FOR INTERCEPTION BY THE NEEDLE AS IT RECIPROCATES ON ITS PATH; AND MEANS FOR ENGAGING THE UNDERLOOPER THREAD BETWEEN ITS ANCHORAGE ABOUT SAID MEMBER AND THE PREVIOUS STITCH TO REFORM THE THREAD TRIANGLE ABOUT SAID MEMBER WHEN THE DIRECTION OF FEED IS REVERSED. 